You depend on your furnace to keep your home warm and comfortable. It’s an unpleasant surprise when your furnace starts to blow cold air. Some of the most common causes are simple to fix, while others require assistance from an HVAC professional.

Here are four possible reasons your furnace might be blowing cold air.

The furnace hasn’t warmed up. You have no cause for concern if you feel cold air when you first turn your furnace on, but the air feels warm after a few minutes. Just as it takes a few seconds to receive hot water from a tap, it’s normal to feel cool air when you first start your furnace. If your furnace blows cold air that never gets warm, you should schedule a service call.

The thermostat is set to “on.” If your furnace blows cold air only intermittently, the problem might be that your thermostat is set to “on” instead of “auto.” When your thermostat is in the “on” position, the fan will run continuously whether the furnace is warming the air or not. Switch the setting to “auto” and the fan will only turn on when the furnace is running.

The furnace is overheating. As a safety measure, your furnace has a limit switch which turns the burners off if the furnace overheats. The fan will continue to blow air after the burners are shut off. Overheating is often caused by a dirty air filter. Dirty filters inhibit the airflow into the furnace, forcing it to work harder to heat your home. Replace your air filter and see if your furnace begins working properly.

The pilot light has gone out. If you have an older gas furnace that’s blowing cold air, the pilot light may have gone out. You can relight it yourself if you’re comfortable doing so. Always follow the manufacturer’s directions for lighting it safely. If you’re not able to light it yourself, or if the pilot light goes out again soon after you re-light it, contact an expert for help.

If you’re experiencing problems with your furnace, contact us today to schedule your heating repairs.